Currently, a large number of electrical and/or electronic devices are supplied with energy by a battery, respectively a battery unit. The terminology, battery, in the sense of the present application, includes, in such case, a single-use battery, a rechargeable battery, and other dischargeable energy storers, respectively energy converters, such as, for example, a capacitor, which can deliver a limited amount of energy. The battery has, in such case, at least one electrically positive, and at least one electrically negative, pole. The device, or especially its electronics unit, can thus be supplied and operated with electrical energy withdrawn from the battery, for example, energy in the form of an electrical current and/or an electrical voltage.
Such battery operated devices are used, for instance, in the field of process automation technology. Thus, for example, field devices can be equipped with a battery operated radio unit, which has a battery unit containing a battery. In this connection, it is known to supply both the radio unit as well as also the connected field device with electrical energy from the battery of the battery unit. Furthermore, autarkic field devices exist, which have a battery, which serves for supplying the field device with the energy required by the field device. The terminology, field devices, means, in such case, in principle, all devices, which are applied near to the process and which deliver or process information relevant for the process. Besides the earlier mentioned measuring devices/sensors and actuators, also considered to be field devices are generally units, which are connected, for example, directly to a fieldbus and serve for communication with superordinated units—thus, units such as e.g. remote I/Os, gateways, linking devices and radio units. In the case of battery operated field devices, of course, it is desired to increase their operating time, respectively service life, as much as possible. Currently known from the state of the art are numerous methods and circuits directed toward this goal.
However, in explosion-endangered zones special requirements govern the application of electrical and/or electronic equipment. Thus, it is, for example, known from the state of the art to use battery driven field devices in explosion-endangered zones. Such field devices make use of electrical current- and/or voltage limiting, in order to meet these special requirements. In such case, corresponding means for electrical current- and/or voltage limiting are provided for the electronics unit in the region of the battery connection as well as also in the battery itself, in order to block ignition-capable amounts of electrical energy. These Ex-limiting measures do, however, due to the means for electrical current- and/or voltage limiting in the connection region of the field device as well as also in the battery unit, result in a not insignificant loss of power. This power loss, which cannot be utilized, shortens the service life of the battery.
Devices that are provided exclusively for operation in a non-explosion endangered region do not have these electrical current- and/or voltage-limiting measures. The percentage of applications for non-explosion endangered zones lies today at about 80-90% of all applications.
For reasons of cost, it is often advantageous not to manufacture two variants of a battery unit, respectively battery operated field device, so that, most often, the Ex-variant of the battery, respectively the field device, is applied also in the non-Ex region. Due to the high energy consumption resulting from the Ex-limiting measures, one is, however, frequently compelled to manufacture and/or to offer either the battery unit and/or the field device also without the Ex-limiting measures.
Moreover, field devices, such as sensors, actuators or display- and/or service units, depending on functionality, such as, for example, the used measuring principle, require different amounts of energy, and, thus, have different power- and/or energy consumptions. It is, consequently, necessary to manufacture different variants of battery units and/or electronic units, in order to provide an energy supply generally matched to the function of the field device or, in general, the device.
Due to the large number of manufacturers of (field-)devices and (field-)device types, there are currently different forms of housings for battery units and electronics units as well as different contactings of such. In such case, a certain battery unit is, most often, matched specially to a single device, or device type, and, consequently, only applicable in combination with such. Furthermore, the electrical power withdrawable from a battery unit is, most often, predetermined by the no load voltage between the, usually, two contacts of the battery unit and is, thus, not variable.